Keithley 2657A, Reference Manual, Page: 701 / 805

Section 9: Frequently asked questions (FAQs) Model 2657A High Power System SourceMeter® Instrument Reference Manual
9-8 2657A-901-01 Rev. B/December 2012
(1) Protective earth (safety ground). Keithley Instruments Model CA-568-120 is a protective
earth cable assembly (
http://www.keithley.com
) for
ordering information.
(2) Model 2657A interlock digital I/O. Pin 24 (INT) and pin 22 (5 V DC) are connected to the
test fixture lid switch. The interlock switch is shown in the disengaged, or lid open, position.
(3) Normally-open (NO) interlock metal safety enclosure.
(4) To protective earth (safety ground) from the test fixture or protection module. Additional
connections for redundant protective earth may be required.
(5) HI and LO connections using Model HV-CA-571-3 high-voltage triaxial
female panel mount to unterminated cable assembly. LO is connected to the metal noise
shield.
(6) High-voltage triaxial cable assembly (Model HV-CA-554)
(7) Model 2657A.
Low-current measurement programming example
Example code for a typical low-current measurement is shown below. This code assumes that a
100 G
Ω resistor is being tested.
-- Restore defaults.
smua.reset()
-- Set source to DC V.
smua.source.func = smua.OUTPUT_DCVOLTS
-- Select 200 V source range.
smua.source.rangev = 200
-- Output 100 V DC.
smua.source.levelv = 100
-- Select 1 nA range.
smua.measure.rangei = 1e-9
-- Set current limit to 2 nA.
smua.source.limiti = 2e-9
-- Turn on output.
smua.source.output = smua.OUTPUT_ON
-- Delay 1 second to allow for source and measure settling.
smua.source.delay = 1
-- Returns current reading.
print(smua.measure.i())
-- Returns resistance reading.
print(smua.measure.r())
-- Turn off output.
smua.source.output = smua.OUTPUT_OFF
How can I change the line frequency or voltage?
The Model 2657A requires a line voltage of 100 V AC to 240 V AC (±10%), and a line frequency of
50 Hz or 60 Hz. At the factory, each Model 2657A is configured to match the power line frequency
appropriate for your country (either 50 Hz or 60 Hz).
You can manually configure the instrument to a different line frequency. For more information, see
Line frequency configuration (on page 2-9).